The invention relates to active adaptive attenuation systems.
An active adaptive attenuation system has an output transducer outputting a control signal combining with a system input signal to yield a system output signal. An error transducer senses the system output signal and outputs an error signal to an adaptive filter model having a model input from a reference signal correlated to the system input signal, and a model output outputting a correction signal to the output transducer. Active adaptive attenuation systems are particularly useful in cancellation or control of sound and vibration.
The present invention provides a second adaptive filter model having a model input from the correction signal, an error input from the error signal, and a model output supplied to the model input of the first model. The resulting recursive controller is particularly useful as an active adaptive attenuation system since the second model can directly model and compensate for feedback from the output transducer to the input transducer. In one desirable aspect, the invention enables faster convergence of the overall system.